Field of the invention
The present invention relates to an image reading device which reads an image of an original to obtain an image signal. In more detail, the present invention relates to the image reading device which performs place-and-image reading of the image of the original which is statically placed by a scanning unit moving in a longitudinal direction of the original.
Description of the Related Art
JP 2012-108424 A discloses an example of this type of conventional image reading device. In the image reading device disclosed in JP 2012-108424 A, a reading unit elongated. in a main scanning direction reciprocates in a sub scanning direction to read the image of the original. Herein, communication of an electrical signal between the reading unit being a moving body and a housing which does not move is performed by a flexible flat cable (hereinafter, referred to as “FFC”). Furthermore, a protective film is arranged between the FFC and an original platen.
However, the above-described conventional technology has a following problem. That is to say, the FFC has a short life time. This is because the FFC is arranged in a bent manner and a direction of the bend is reversed in a part of the FFC due to the movement of the reading unit.
This is described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a reading unit 100 of this type. Although it is not illustrated in detail in this drawing, a direction. perpendicular to a paper face is a longitudinal direction (main scanning direction) of the reading unit 100. A horizontal direction indicated by arrow X in the drawing is a direction in which the reading unit 100 moves. Although it is not illustrated, the original to be read is placed above the reading unit 100 in the drawing such that a surface to be read faces downward. A FFC 102 is connected to the reading unit 100. The FFC 102 is arranged in a state bent into a U-shape between the reading unit 100 and a housing 101. FIG. 1 illustrates a situation in which the reading unit 100 is located in a leftmost position in a range of movement thereof. In this state, a portion in a range B in the drawing of the FFC 102 is bent into the U-shape. The FFC 102 in a bent section is bent to be convex with respect to the reading unit 100 and the housing 101.
A cross-sectional view in a state in which the reading unit 100 is moved rightward from the state illustrated in FIG. 1 is illustrated in FIG. 2. In FIG. 2, as compared to FIG. 1, the reading unit 100 is displaced rightward. According to this, the FFC 102 is widely bent into the U-shape where this protrudes leftward in the drawing from the reading unit 100. Herein, when the FFC 102 in FIG. 2 is examined in detail, it is understood that this is bent in a direction opposite to that in the description above in a portion in a range C. That is to say, the FFC 102 in the range C is bent to be convex with respect to the reading unit 100. Of course, the FFC 102 in the range C is bent to be convex when the reading unit 100 is located on a left end as in FIG. 1. Therefore, in this range, the direction of the bend of the FFC 102 is reversed by the movement of the reading unit 100. The FFC 102 fatigues to cause disconnection because the bend is repetitively reversed.
Especially, when the FFC 102 in which a shielding layer or an impedance adjusting layer is stacked on one surface side of a transmitting layer thereof is used, this problem is significant. Such FFC has a structure asymmetrical in a thickness direction, so that the transmitting layer is located in a position displaced from the center in the thickness direction. Therefore, it is changed between a state in which the transmitting layer is compressed in a longitudinal direction and a state in which this is extended in the longitudinal direction each time the bend is reversed.